The previous two pages defined fundamental units of mass, distance,
and time. This page adds some derived notions: force, energy, pressure, and
power; velocity and acceleration.

The first four lines are in two parts each. The left part defines an
abstract quantity like force or energy; the right part defines a unit
of that quantity like newtons or joules. For example, the second line defines energy and units of energy. The left side says that energy
is equal to mass
times distance
squared divided by time squared. (This is the first appearance of the glyphs for distance and time.)
The right side says that a joule
of energy is !!1\frac{\mathrm{kg}\,\mathrm{m}^2}{\mathrm{s}^2}!!.

The two following lines define the abstract concepts of velocity (which has
appeared before in connection with the speed of light) and
acceleration (which is
new). There are no units given for these.

Concept

force

energy

pressure

power

velocity

acceleration

Unit

newton

joule

pascal

watt

(none)

(none)

The newton and the joule won't appear again. Force won't appear again
except on the last page, which asks “force WTF?”.

The final part of the page is the most interesting. It mentions the
Planck constant !!h!!
(not the related !!\hbar!!) which is
!!6.6260755\cdot 10^{{}^-34}!! joule-seconds and the universal gravitation constant !!G!!
which is !!6.67259\cdot 10^{{}^-11}\; \mathrm{m}^3\;
\mathrm{kg}^{{}^-1}\; \mathrm{s}^{{}^-2}!!.

It's quite possible that the recipients won't recognize the gravitational
constant, which is tricky to measure directly. Newton's law of
universal gravitation was known on Earth for hundreds of years before
the value of !!G!! was worked out. But if the recipients don't know
it, they will be able to work it out from the later statements about
the mass and radius of the Earth and the gravitational force at its
surface, This would in turn allow them to calculate the mass of their
own planet.

Note that on this page some
inverse units are written with a division sign and some with a
negative exponent. Will this inconsistency puzzle the aliens? My
coworker Jeff Ober suggests that it communicates the important
personal information that humans are confused and inconsistent.

The next
article will discuss page 10, shown at
right. (Click to enlarge.) Try to figure it out before then.